The goal of this research is to understand neural mechanisms responsible for analyzing complex vocal signals. The integration of spectral and temporal information is essential for the analysis of complex signals found in social vocalizations. Such integration was once thought to be a primary function of the auditory forebrain. This type of integration, however, occurs in lower auditory nuclei. The inferior colliculus (IC) of the mustached bat is a midbrain structure known to process complex stimuli by integrating spectro-temporal information. This integration is known as combination sensitivity. Combination-sensitive neurons respond best when distinct aspects of spectral information are combined in a specific temporal order. The neural mechanisms that contribute to combination sensitivity may provide us with a better understanding of how the auditory system processes complex sounds such as speech. Therefore, this research application seeks to examine the effects of the excitatory neurotransmitter glutamate on combination-sensitive neurons in the IC of mustached bats. Studying the physiology of combinatorial neurons may assist in the understanding of pathologies that affect the auditory system and their role in human communication disorders.